This was my diffuser before I cleaned it. Gross!
Before you use these directions, be aware that this may void your warranty. I picked up both of my diffusers for around $12, so they weren't expensive. Both are past their warranty, too.
This is the essential oil diffuser that I have. The price went up a little bit, but it's still a great deal.
Always check the manufacturer's instructions in the booklet or online before cleaning yours.